9 research outputs found
Spectroscopic, structure and DFT studies of palladium(II) complexes with pyridine-type ligands
Five palladium(II) complexes with pyridine
derivative ligands have been synthesized. The molecular
structures of the complexes were determined by X-ray
crystallography, and their spectroscopic properties were
studied. Based on the crystal structures, computational
investigations were carried out in order to determine the
electronic structures of the complexes. The electronic
spectra were calculated with the use of time-dependent
DFT methods, and the electronic spectra of the transitions
were correlated with the molecular orbitals of the complexes.
The emission properties of the complexes have
been examined
Interactions of amino acids with aluminum octacarboxyphthalocyanine hydroxide. Experimental and DFT studies
The influence of albumin and amino acids (l-serine, glycine, l-histidine, l-tryptophan, l-cysteine) on the properties of aluminum octacarboxyphthalocyanine hydroxide (Al(OH)PcOC) was investigated in a phosphate buffer (pH 8.0). Particular attention was paid to the spectroscopic properties and photostability of Al(OH)PcOC. The effect of albumin or amino acids on the photodegradation of Al(OH)PcOC was examined in water using red light: 685 nm and daylight irradiation. Analysis of kinetic curves indicated that interaction with those molecules increases the photostability of Al(OH)PcOC. The molecular structure of Al(OH)PcOC complexes (in vacuum and in water) with axially or equatorially coordinated amino acids was studied by the B3LYP/6-31G* method, and the effects on molecular structure and electronic absorption spectrum were investigated on the basis of the density functional theory. The calculation results revealed that axial coordination significantly reduces the non-planarity of the phthalocyanine ring, and, thus, alters the electronic structure. On the other hand, hydrogen bonding of phthalocyanine side COOH groups with amino acids, in equatorial complexes, does not change the structure within the center of the phthalocyanine, and causes only a slight increase in UVâvis bands intensity, which is in perfect agreement with experimental data. [Figure not available: see fulltext.
A ruthenium(II) hydride carbonyl complex with 4-phenylpyrimidine as co-ligand
The reaction of [RuHCl(CO)(PPh3)3] with
4-phenylpyrimidine gave a new ruthenium(II) complex,
namely [RuHCl(CO)(PPh3)2(pyrim-4-Ph)]. The complex
has been studied by IR and UVâvis spectroscopy and by
X-ray crystallography. The molecular orbitals of the
complex have been calculated by density functional theory.
The spin-allowed singletâsinglet electronic transitions of
the complex have been calculated by time-dependent DFT,
and the UVâvis spectrum of the compound has been
discussed on this basis. The emission properties of the
complex were also studied
Interactions of amino acids with aluminum octacarboxyphthalocyanine hydroxide. Experimental and DFT studies
The influence of albumin and amino acids (l-serine, glycine, l-histidine, l-tryptophan, l-cysteine) on the properties of aluminum octacarboxyphthalocyanine hydroxide (Al(OH)PcOC) was investigated in a phosphate buffer (pH 8.0). Particular attention was paid to the spectroscopic properties and photostability of Al(OH)PcOC. The effect of albumin or amino acids on the photodegradation of Al(OH)PcOC was examined in water using red light: 685 nm and daylight irradiation. Analysis of kinetic curves indicated that interaction with those molecules increases the photostability of Al(OH)PcOC. The molecular structure of Al(OH)PcOC complexes (in vacuum and in water) with axially or equatorially coordinated amino acids was studied by the B3LYP/6-31G* method, and the effects on molecular structure and electronic absorption spectrum were investigated on the basis of the density functional theory. The calculation results revealed that axial coordination significantly reduces the non-planarity of the phthalocyanine ring, and, thus, alters the electronic structure. On the other hand, hydrogen bonding of phthalocyanine side COOH groups with amino acids, in equatorial complexes, does not change the structure within the center of the phthalocyanine, and causes only a slight increase in UVâvis bands intensity, which is in perfect agreement with experimental data. [Figure not available: see fulltext.
Photochemical Kinetics of Pyruvic Acid in Aqueous Solution
International audiencePyruvic acid in the atmosphere is found in both the gas and aqueous phases, and its behavior gives insight into that of other alpha-keto acids. Photolysis is a significant degradation pathway for this molecule in the environment, and in aqueous solution the major photoproducts are higher-molecular-weight compounds that may contribute to secondary organic aerosol mass. The kinetics of the aqueous-phase photolysis of pyruvic acid under aerobic and anaerobic conditions was investigated in order to calculate the first-order rate constant, J(aq), in solution. Analysis of the exponential decay of pyruvic acid was performed by monitoring both pyruvic acid and its photolytic products over the course of the reaction by H-1 NMR spectroscopy. Detection of major and minor products in the 0.1, 0.05, and 0.02 M pyruvic acid photolyses clearly demonstrates that the primary reaction pathways are highly dependent on the initial pyruvic acid concentration and the presence of dissolved oxygen. The J(aq) values were calculated with approximations based on the dominant pathways for limiting cases of the mechanism. Finally, a model study using the calculated rate constants demonstrates the importance of aqueous-phase photolysis as a sink for pyruvic acid in the atmosphere, compared with gas-phase photolysis and OH oxidation